LH A320 Rough Landing @ Hamburg

[Chris Scott]

Airbus FBW - Background

Quote from Rananim [Today/00:57, currently#320]:
I have to reference this to what I know,which is Boeing.If during/after landing,no right-roll input is made by co-pilot,this would be clearly and instantly apparent to the Captain(before the wing has a chance to rise).On the Boeing.However,on the Airbus,he cant see/feel what the co-pilot is commanding so he can only react until/when the upwind wing starts coming up.Plus he has to press an override button for his sidestick to take control.Am I right?
[Unquote]

For an ex-A320 pilot's thoughts on sidestick aspects, see my post #229 [Mar04/19:07]. CONF iture [Today, 04:59, currently #330] has put the case against the Airbus sidestick succinctly. You have read his post. But he is wrong when he argues for Direct Law – in roll only – for the final approach. At what stage would it be introduced, and how suddenly? I can assure him that the transition from Normal Law to Direct Law with gear extension – in some failure cases – is one most A320 pilots contemplate with trepidation, because the handling changes so much in roll, as well as pitch.

The differences between Airbus and Boeing are honourable ones, dating from the mid-1980s, when Bernard Ziegler (head of Airbus FBW engineering design) made at least two radical and irrevocable decisions on A320 design. These were based, I believe, on engineering considerations of simplicity, reliability, and weight-saving; as follows –
1) The throttle levers would be FBW; with no cable connections, and no motors to drive them forward or backward in mimicry of autothrottle commands. In manual thrust, however, their transducers would send throttle-by-wire signals to the FADECs in response to the pilot's movement of the levers.
2) The sidesticks would: (a) not be interconnected [to save the weight and jamming risks of cables]; and (b) not move to mimic AP commands when the autopilot was engaged. The inputs of the sticks would be algebraically summed, except that there would be a means of one stick being prioritised by its AP-disconnect push-button.

BALPA pilots, as well as others engaged in technical study, tried hard to persuade Airbus to change some or all of the above, but Mr Ziegler prevailed. On the first conversion course at Blagnac, ordinary airline pilots first flew the simulator in January 1988, and the aeroplane in February/March. We found that - although some of us still had reservations on the throttle and sidestick logics – the bottom line was that the OVERALL PACKAGE was more than acceptable. Twenty years later (14 of them line-flying the A320 family), I think this assessment has been vindicated by the safety record, which compares very favourably with other types.

The A320 was formally type-certificated while we were on the course, and we put it into service in the Spring. Even as late as 1989, however, IFALPA was in formal discussion with Bernard Ziegler at a meeting hosted by Airbus test/training pilots. My talented copilot from our conversion course, Richard P, put a strong case for modifications to the auto-thrust logic on our behalf; but was successful only in obtaining a DMC mod to improve the presentation of current IAS on the PFD. The non-driven-autothrottle-lever debate was over, and we had decided that the sidestick logic was acceptable, if not ideal for training/monitoring situations.

So is the current crop of Airbuses over-automated, leading to pilots being out of the loop and/or lazy?
Has Boeing found a better balance, or is it merely following in the safe wake of Airbus?
Automation was nothing new in 1988. For example, even the ageing B707s I flew in the 1970s had a yaw-damper, anti-skid brakes, and thrust-reverser inhibition in flight.
But we had to select our own spoilers on landing (no lift-dumpers) and there was no autothrottle, no auto-land, and no rudder-fine steering.
Like Airbus; all the others – including Boeing – have moved a long way in automation since then, and the trend continues inexorably...